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One key to a longer life may be a quieter brain without too much nerve activity, according to a new study examining brain tissue after the death of extremely long-lived people for clues about what makes them different from people who died in the 1960s and 1970s.
"Use it or lose it" has dominated thinking about how to protect the aging brain, and extensive research has shown that there are many benefits to staying physically and mentally active as people age. But the study, published in the journal Nature, suggests that it's not always better. Excessive activity – at least at the level of brain cells – could be harmful.
"The most shocking and puzzling thing about this new book is … [brain activity] is what you feel is about maintaining your cognitive-normal state. the idea that you want to keep your brain active in later life, "said Michael McConnell, a neurologist at the Liberian Institute for Brain Development who did not participate in the study." What is super unexpected is … restricting nerve activity is a good thing in healthy aging. This is very counter-intuitive. "
Researchers at Harvard Medical School analyzed brain tissue donated to human brain banks by people in their 60s and 70s, who were 100 and older. They found people who died before the mid-1980s had lower levels in their brains of a protein called REST, which suppresses genes involved in sparking brain activity, than the oldest people. that he was protected against Alzheimer's disease, but they weren't sure if REST was any in the way it protects people from death or is simply a sign of further aging.
Since it is not currently possible to measure REST in the brains of living humans, scientists have begun experiments with roundworms and mice to test whether it plays a role When researchers increase the activity of the worm version of REST, the brain activity of the worms decreases and they live longer. The opposite happened when scientists deactivated the REST-like gene in circular worms "Methuselah", which have many long life; the worms' nervous activity increased – and their lives were dramatically shortened. REST-deprived mice were also more likely to have more loaded brains, including seizure-like seizures.
"I think it's overactivity, excitation out of control – it's not good for the brain. You want neurons to be active when and where you want them to be active, not to shoot as a whole, "said Cynthia Canyon, vice president of aging research at Calico Labs, which praised the design of the study, but said that she believes The nervous system is just one of many tissues that have an impact on life expectancy
It is not yet clear how these differences in brain activity at the cell level could translate into differences in knowledge or behavior in humans. Yankner, professor of genetics and no The head of work at Harvard Medical University said his lab was already monitoring to see if targeting REST with drugs could lead to new treatments for neurodegenerative diseases or aging itself. it is also interesting to understand how alternative interventions, such as meditation that affects neural rhythms, could act as a cure for early memory loss, Yankner said.
"I think the implications of our study are that with aging there is some aberrant or harmful neural activity that not only renders the brain less effective but is detrimental to human or animal physiology and reduces life expectancy as a result." says Jankner.
The donated brains that the researchers examined came from people who died for various reasons, making it impossible to see whether the difference in REST was related to the likelihood of death.
Angela Gutchez, a professor of psychology at Brandeis University, said when people get old and tested in brain scanners, there are many changes in activity in the prefrontal cortex, the part of the brain where Harvard researchers have examined REST.
In some cases, according to her, studies wn older adults activate more brain circuits than younger people to complete a task. But the implications of this change are unclear: These activation patterns may be indicative of a less efficient brain in the elderly or attempts to compensate.
One model, called CRANCH, attempts to explain changes in patterns of brain activation with age. It says that when people try harder and more difficult tasks, they activate more areas of their brain until they reach a step where their mental resources are exhausted. Older people have an earlier break point and cannot activate as many regions. Another called "STAC" says that older adults have natural differences in their basic scaffold of natural cognitive resources, and these options influence how and whether people can engage more neural regions when faced with difficult tasks.
Gutchess stated that the new study was intriguing and a reminder that to understand the truly aging brain, it would be necessary to connect the dots between observations and models from scientific laboratories that focus on many different scales ranging from human behavior to an image of the brain, to the functioning of individual cells.
"We have to overcome different levels of experience," Gutchez said.